Select the scatter file inside the stock ROM folder of the device you want to flashSelect either Download only, Firmware Upgrade or Format + Download from drop down menuClick Download ButtonNow turn off and connect your device to PCWait for flashing process to completeReboot deviceIf there was no cache or userdata inside the ROM folder, you might need to factory reset device from recovery after flash

For a more detail guide with video and pictures on how to use SP Flash Tool, click here